In a previous (now closed) thread, the question of ownership of the area surrounding a grade crossing was posed. In my current job, I have the opportunity to look at tax maps to determine tax numbers (we call them SBL for section, block and lot). As a railroad enthusiast, of course I am always distracted when looking for zoning and building issues and find myself checking out the LIRR ROW as shown on the maps. (The Southold station is right outside my office window, so that's another distraction...but I digress.) Interestingly, if one follows the tracks along the map, wherever, and without exception, the RR crosses the roads, the RR ROW stops, and resumes again across the roadway.
In other words, the railroad ROW is not a continuous multi-mile long strip of land, with one SBL#. It is a bunch of short strips, interrupted at every grade crossing. Each segment has its own unique SBL#.
Scroll in with the mouse to get a close-up of the railroad, and you'll see what I mean. This is just offered as some food for thought. I'm not sure of how it works in other jurisdictions, but that's how it appears here. To find the exact places that I'm talking about, the railroad is evident as a really straight line, and is named simply "LONG ISLAND" not LIRR or MTA.
Also, there's a spot where the LIRR passes over State Road 25, in Mattituck. It appears that the RR bridge is owned by the State of NY, as it is part of the highway property as drawn on the map.